When a first MFP that manages first and second conversion values of user authentication information accesses a second MFP, the first MFP queries about which conversion value is used by the second MFP to execute user authentication processing. The first MFP transmits information based on a conversion value in accordance with the query result to the second MFP. Then, the second MFP executes user authentication processing using information based on a conversion value in accordance with the query result and a conversion value managed by the second MFP.